Page "Binary function" Paragraph 13

Similarly, given any element y of Y, there is a function f < sub > y </ sub >, or f (·, y ), from X to Z, given by f < sub > y </ sub >( x ) := f ( x, y ).

( In computer science, this identification between a function from X × Y to Z and a function from X to Z < sup > Y </ sup > is called Currying.